WO2016079075A1

WO2016079075A1 - Electronic liquid sensor for vacuum treatment device

Info

Publication number: WO2016079075A1
Application number: PCT/EP2015/076736
Authority: WO
Inventors: Pierre Croizat; Martin Deibler; Chris Dawber; James Edward STEIN
Original assignee: Paul Hartmann Ag
Priority date: 2014-11-19
Filing date: 2015-11-17
Publication date: 2016-05-26
Also published as: DE102014116910A1

Abstract

The invention relates to a device for providing vacuum for the vacuum treatment of wounds on the human body or animal body. The device can be worn on the body of a user and/or is stationary. The device comprises an electrically driven or electrically drivable pump that produces the vacuum, a connection for a suction line leading to the wound location, a vacuum connection, a filter, an electronic control unit for the pump, and an electronic liquid sensor for detecting liquid. The invention further relates to the use of an optoelectronic sensor in conjunction with a device for providing vacuum for the vacuum treatment of wounds.

Description

Title: Electronic fluid sensor for negative pressure therapy device

description

The invention relates to devices and methods for providing negative pressure for medical applications, in particular devices for negative pressure therapy of wounds on the human or animal body and their use. The

Devices include a pump, a port for a suction line, a vacuum connection, a filter, a control unit and an electronic fluid sensor.

Vacuum therapy of wounds, also referred to in the field as TNP (topical negative pressure) or NPWT (negative pressure wound therapy), has been known for a long time, but has been used increasingly since the mid / late 1990s in particular. In this case, a wound filling material is usually inserted into the wound, the wound area covered with a foil and by means of a

Drainage tube and a vacuum pump generates a negative pressure in the wound space. By using the wound filling material, the pressure is evenly distributed over the wound. The negative pressure causes, especially in the initial phase of wound treatment, an effective wound cleansing by removing wound exudate. As further advantages, especially in the subsequent granulation phase, promotion of the formation of granulation tissue and reduction of the

Called wound edema. The negative pressure therapy is usually until the

Wound closure performed. Wound closure is generally considered to be achieved when there is a layer of epidermis over the former wound site. Wound closure can be achieved through healing processes or through surgical procedures. Negative pressure therapy is used in particular in acute or chronic wounds, for example in ulcers (eg pressure sores, diabetic, neuropathic or venous ulcers), traumatic wounds, therapy-resistant wounds, infected wounds, postoperative wounds, probed fistulas, as well as

Skin flaps and skin grafts. Chronic wounds are characterized by slow or absent wound healing.

A conventional device for negative pressure therapy of wounds usually comprises a suction pump (also referred to in the art as "vacuum source"), one or more sensors for pressure monitoring, a control unit for

Control of the pump including a data memory, user controls (eg, switches, indicator lights or display), terminals for data communication, a power supply for the pump and the control unit (for example, an accumulator and / or a power supply), a fluid receptacle for Intake of body fluids extracted from a wound, a port for one or more wound suction lines, filters to prevent ingestion of body fluids into the pump, and vacuum connections by means of which fluid communication between the individual components can be established.

Devices for negative pressure therapy of wounds are known in the art. Suitable negative pressure therapy equipment and accessories will be

For example, in the documents WO201 1018132, WO201 1018133, WO2012156140, WO2012156174, WO2012163617 and WO2013159904 described. Documents WO2014023501 and WO201 1076340 disclose suitable vacuum port means (port) for establishing a vacuum connection with the wound dressing. In the wound space, for example, from the documents WO2010072309,

WO2012022484, WO201 1072840, WO2012167942 or WO201 1003521 known wound dressings are introduced. According to the Applicant's experience, a wound dressing made of an open-celled polyester polyurethane foam, which is described in more detail in WO2012022485, has proven to be particularly advantageous in vacuum wound treatment. Devices for negative pressure therapy of wounds are commercially available. The range of devices available on the market includes small, portable devices that allow patients a degree of mobility through to stationary devices, such as long-term care facilities. Furthermore, devices are available, as described for example in WO201 1018132 or WO201 1018133, which are suitable for both stationary and mobile operation. For the

Vacuum therapy suitable accessories, such as wound dressings, other dressing components or connecting means is also commercially available.

The term "fluid" is used in this document as a collective term for

Liquids (for example, water, rinsing liquids or body fluids) and gases (for example, air or water vapor) are used. Lines (in particular body fluids), gases (in particular air) or mixtures of liquids and air can be present in the lines leading from the wound to the therapy device (suction line, vacuum connection). Liquid may also be present in the form of very fine droplets in the air sucked towards the device. Furthermore, the air can contain a high proportion of water vapor (humid air).

During the negative pressure treatment body fluids are sucked out of the wound area. This may in particular be blood, wound exudate

different proportions of water as well as to deal with rinsing liquids. Rinsing fluid accumulates, for example, in the so-called instillation therapy. This is in the

Change to apply negative pressure a wound-cleansing and / or a wound healing promoting solution applied in the wound area. The in the

Negative pressure typically incurred fluid volumes depend on the particular treatment method used and can be considerable

Are subject to fluctuations. In the post-operative use of negative pressure therapy for the treatment of surgical wounds often only a small amount of fresh blood is aspirated. By contrast, large volumes (up to several liters per day) of bodily fluids with a high water content can occur, for example, in the case of negative-pressure therapy on the open abdomen. In the negative pressure therapy devices known from the prior art (see, for example, the above-mentioned WO201 1018132) are common

Liquid receiving container for receiving extracted from a wound body fluids provided. For reasons of hygiene, these are usually containers which are disposed of after a single use

(Disposable container). Furthermore, there are also systems for negative pressure treatment of wounds, in particular for the treatment of wounds with low exudate levels, in which no liquid container is provided. The

Wound exudate is then stored in such devices usually in the wound dressing, the dressing having liquid-absorbing components, see, for example, WO2009066105.

In any case, in the construction of a device for negative pressure therapy of wounds there is the problem that the extracted body fluids, which are often contaminated with infectious components, must not get into the vacuum source. Ingress of body fluids into the vacuum source can damage the pump or pump components. This can lead to an immediate failure of the pump, so that the therapy must be interrupted and a replacement device must be procured. The ingress of lesser amounts of liquid can shorten the life of the pump. Furthermore, there is a risk that the liquid is sucked through the pump and blown through an outlet of the pump into the interior of the device. This device components can be damaged and contaminated with infectious fluids. In the worst case, infected fluid enters the environment. Contamination of the interior of the device or the environment may occur without the user noticing. Contaminations inside the therapy device may endanger, for example, the technician who later waits for the device. Contaminations in the environment can cause the

Patients who endanger medical personnel as well as other persons in the vicinity of the therapy device.

It is therefore necessary to reliably separate off liquid fractions which are present in the air stream taken in by the pump. A separation of air and liquid usually takes place already by a suitable construction of the Container, if one is provided. As mentioned above, it is also possible to use smaller amounts of body fluids in absorbent layers of the body

Restrain wound dressing. Separation of air and liquid in this case takes place by means of the absorbent layers of the wound dressing.

Body fluids may enter the vacuum source, particularly if the fluid receptacle or other device used to collect the aspirated fluids, such as an absorbent bandage, is full or saturated and the vacuum source is not timely turned off. Furthermore, liquids in the form of small droplets can be entrained by the air flow and thus penetrate into the vacuum source.

The commercially available devices, also referred to herein as negative pressure therapy unit, therefore usually contain a filter in the vacuum line, which is to prevent the ingress of liquid into the pump. For devices having a fluid receptacle, the filter is usually located between the receptacle and the inlet of the pump. Often, the filter, which is usually a microfilter, is securely connected to the container and is disposed of when the container is replaced. In devices without fluid receptacle, in which the wound secretions are stored in the wound dressing, the filter is usually in the dressing component, see the aforementioned WO2009066105. The nature of the filter is such that air can pass but liquid is retained. Furthermore, common negative pressure therapy devices often have a mechanism which ensures that the device is turned off when the container (if any) is full.

During normal operation of the negative pressure therapy device, the above-mentioned filters, optionally supplemented by a shut-off mechanism with a full container, prevent the entry of liquid into the pump.

However, undesirable liquid entry into the line leading to the pump, and thus ultimately into the pump, may occur if the filter is defective. It is conceivable that a filter due to a manufacturing error already at the beginning of the application of negative pressure at least small amounts of liquid through. Such a However, defect can also occur in the case of an initially intact filter during the course of the

Negative pressure operation occur. In particular, it is conceivable that an initially intact filter initially restrains the incoming liquid. The liquid retained by the filter moistens the filter. If the humidified filter is then exposed to sustained negative pressure for a prolonged period of time, for example if the shut-off mechanism malfunctions, the filter can "break through" so that liquid can enter the line leading to the pump.

The inventors involved in the present invention were faced with the task

To improve negative pressure therapy devices. In particular, such therapy devices should be better protected against unwanted ingress of liquid into the negative pressure generating device. It was also desirable to develop methods that would allow safer operation, including the maintenance of such a device. Furthermore, life and reliability of such devices should be increased. From practice also resulted in the

Requirement to ensure effective containment of the aspirated, partially highly infectious bodily fluids, i. It should be reliably prevented that the liquids get inside the device or contaminate the environment of the device.

The objects have been achieved by means of a user-portable and / or stationary device for providing negative pressure for the negative-pressure therapy of wounds on the human or animal body. The device comprises a (in operation of the device) generating the negative pressure electrically driven

or electrically driven pump having an inlet for sucking in air, with an outlet for blowing out air and with an interior which can communicate with inlet and outlet, a connection for a suction line leading to the wound site, a vacuum connection between the connection and the inlet, so that a vacuum communication between the pump and the leading to the wound site suction line can be produced, at least one filter which is impermeable to liquids in the intact state, wherein the filter in the

Vacuum connection is arranged, as well as an electronic control unit for the pump. The device according to the invention is characterized in that the Device further comprises at least one electronic liquid sensor, which can communicate with the control unit, wherein the at least one liquid sensor is arranged downstream of the filter. The expression

"downstream" is in this case based on the fluid flow, which is moved in the intended use of the device in the negative pressure therapy, starting from the wound in the direction of the pump and on to the pump outlet.

The provision of a downstream of the filter arranged electronic

Liquid sensors can improve the operational safety and service life of a

Increase the negative pressure therapy device and facilitate the maintenance of the device. Downstream of the filter, in the fluid system of the device, starting from the filter, there are substantially the following sections:

i) Immediately downstream of the filter is normally the section between the filter and the inlet of the pump. The section between the filter and the inlet of the pump is usually formed by a conduit means, for example by a silicone tube. It would also be possible in principle to attach the filter directly to the inlet of the pump. In that case there will be no conduit between the filter and the inlet of the pump.

ii) Farther downstream is the pump, which can move the fluid flow during operation. The pump includes an inlet for sucking in air, a

Interior through which the fluid flow is moved through and an outlet for blowing out the fluids. The interior can mutually communicate with both the inlet and the outlet when the pump is actuated.

iii) The outlet can open into an opening so that the fluids are released directly into the atmosphere. Alternatively, further fluid flow conductive components may be present downstream of the outlet. The "outlet portion of the pump", as used herein, includes conduit means downstream of the outlet of the pump or other cavities, the downstream opening of which then discharges into the atmosphere. In particular, the area of the outlet often comprises noise attenuation elements and / or in practice

Odor absorbers. The suction line leading to the wound site can be connected to a vacuum dressing, which usually comprises at least one wound dressing and an airtight cover (typically a self-adhesive film), the cover being adhesively fixed to the intact skin surrounding the wound. The wound dressing is often an open-cell foam, for example the polyester polyurethane foam described in the aforementioned WO2012022485, which can optionally be applied in conjunction with an additional wound contact layer. The vacuum communication between the suction line and the wound dressing is normally made by a vacuum connection means (port). The dressing components referred to herein are commercially available, for example under the name of Hydro film ^® (air-tight covering), "VivanoMed ^® Foam" (polyester-polyurethane), "VivanoMed ^® Silicone Layer" (wound contact layer), and "VivanoTec ^® Port" (vacuum connection means) , each from the manufacturer Paul Hartmann AG (Germany). The vacuum generating electrically driven or electrically driven pump is often a diaphragm pump, which is controlled and controlled by the electronic control unit.

In principle, any conventional suction pump can be used within the scope of the invention. The electronic control unit is preferably a programmable control unit which can communicate with an external electronic device via an interface, for example a USB interface. By means of the communication connection with the external device, for example with a portable computer, the control unit can be programmed and / or stored on the control unit as part of a maintenance

Operating data to be queried. While performing the negative pressure therapy, the external electronic device is normally not connected to the device. The electronic control unit preferably comprises operating elements, for example a touchscreen, by means of which a user can control the

Activating or deactivating the negative-pressure therapy device and the parameters desired for the therapy procedure (in particular the amount and duration of the negative pressure to be applied or, if appropriate, a complex therapy schedule) alternating phases of higher or lower negative pressure) can enter. A negative pressure therapy unit with an electrically driven pump, with electronic control unit and with touchscreen is commercially available, for example, under the name "VivanoTec ^® negative pressure unit" from the manufacturer Paul Hartmann AG (Germany).

The vacuum connection between the inlet of the pump and the connection for the suction line makes it possible to establish a vacuum communication between the pump and the suction line. The vacuum connection is normally one or more interconnected conduit sections made of plastic. The vacuum connection and / or the wound suction line should be of suitable length so that the device can be provided spaced from the wound site. Insofar as the device has an optional existing liquid receptacle, the receptacle interior can also form a part of the vacuum connection when the receptacle is arranged between the pump and the connection.

In the vacuum connection, a filter is arranged, which is permeable to the sucked air in the dry state and at the same time blocks the passage of liquid to - at least in the intact state - the ingress of liquid in

downstream of the filter to prevent existing portions of the fluid system.

Examples of suitable filters include membrane filters (for example made of cellulose layers) or filters made of a porous solid (for example a ceramic material, a plastic material, a metal or a sintered body). In the case of filters based on porous solids, one or more additional swellable components may advantageously be present (for example carboxymethyl cellulose), which block the passage of fluid as soon as the filter is soaked through.

According to the invention, at least one electronic one is downstream of the filter

Liquid sensor arranged. The at least one electronic liquid sensor can accordingly

i) between the filter and the inlet of the pump, and / or ii) at the inlet of the pump and / or

ii) in the interior of the pump and / or

iii) at the outlet of the pump and / or

iv) be arranged at the region of the outlet of the pump.

Preferably, at least one electronic fluid sensor is disposed in the section between the filter and the inlet of the pump (section i) and / or in the region of the outlet of the pump (section iv).

The advantages achievable with the invention can often already be achieved with a single, arranged downstream of the filter electronic liquid sensor. This should then preferably be mounted in the section between the filter and the inlet of the pump.

According to its arrangement in the fluid system of the device, the at least one electronic fluid sensor may be downstream of the filter

Detect ingress of liquids. Penetration of liquid in

Sections of the fluid system present downstream of the filter can occur in practice, in particular in the case of a defective filter. The electronic fluid sensor is thus provided in particular for the detection of fluid, which has undesirably penetrated through a defective filter in the downstream of the filter existing portions of the fluid system.

Preferably, the device comprises an electronic liquid sensor, which is arranged between the filter and the inlet, as a result

Liquid entry can already be detected before the liquid has penetrated into the pump. When using the preferred embodiment of the invention mentioned here, it is namely possible, the pump already immediately after

Detection of liquid in the section leading to the pump

Disconnect negative pressure connection before liquid enters the pump. In this way, a contamination of other device components and even the environment in which the device is used to be prevented. The invention thus also includes a device of the type described herein, wherein the electronic control unit can deactivate the pump immediately after a detection of liquid in the present between the filter and the inlet portion of the vacuum connection. In particular, this can prevent liquid from being sucked through the pump and via the outlet from the closed fluid system

is blown out. In this case, advantageously, the low response threshold of an electronic fluid sensor and the high processing speed of an electronic control unit can be utilized.

Alternatively or additionally, it is possible when addressing the electronic

Liquid sensor, an audible and / or visual warning signal to alert the user to the ingress of liquid in the downstream of the filter section of the fluid system.

According to a preferred embodiment of the invention, a sensor signal for immediate shutdown of the pump and for outputting a warning signal (visually and / or acoustically). At the same time, the event becomes electronic

Control unit belonging to electronic memory. Optionally, an additional message via a remote data communication could be issued if the device has a corresponding communication device. It would then be possible, among other things, to alert the medical care staff and / or a service center of the device manufacturer to the defective filter.

According to a further particularly preferred embodiment of the invention, a sensor signal leads to the immediate switching off of the pump, to the issuing of a warning signal and to the blocking of the negative pressure therapy unit for the user. The blockage of the negative pressure therapy unit can only be canceled by a service technician of the device manufacturer, but not by the user. This is a security measure, which should ensure that a possibly with

Wound-secreted contaminated device is no longer used and instead checked expertly.

Alternatively or additionally, the response of the electronic liquid sensor in an electronic memory belonging to the electronic control unit be held. In addition to the response of the sensor and, where appropriate, the intensity or the course of the sensor signals, the time of the event or the events should be registered. The stored information for the response of the sensor can then be retrieved, for example in the course of maintenance of the device. The maintenance technician thus receives instructions in the

Past events that may indicate a defective filter. Corresponding messages for liquid entry could then give rise, for example, to a check or replacement of the pump. Furthermore, the technician receives the indication of a possible contamination of the interior of the device by body fluids. Accordingly, the device could then be disinfected or completely put out of service. When selecting the measures to be taken, the number and type of sensor messages can also be used. So it could be possible to a certain extent to make a conclusion on the amount of liquid infiltrated on the frequency and intensity of the sensor signals. The invention therefore includes the use of a liquid sensor in a negative pressure therapy device of the present invention

described manner for detecting liquid entry in downstream of the filter disposed portions of the fluid system as part of a security check or maintenance of the device. The invention also contemplates the use of the liquid sensor to protect the pump, the device, and the environment

Contamination.

Likewise, the invention comprises a maintenance method for the detection of

Liquid entry in downstream of the filter disposed portions of the

Fluid Systems. The maintenance procedure includes the following steps:

i) providing a device as described above,

ii) subsequently retrieving the memory contents of the electronic control unit to check if any fluid entry has occurred in downstream portions of the fluid system during the preceding operation, iii) subsequently, if appropriate, documentation of the check. If the storage contents contain messages which are located downstream of the filter during a previous liquid entry

Points of the fluid system point, must therefore be assumed that a liquid inlet into the pump. Portions of the vacuum connection disposed downstream of the filter also indicate that the filter has malfunctioned in one or more of the previous uses of the devices. Furthermore, there is a risk of damage to the pump by the liquid penetrated. In the worst case can

Body fluids have been sucked through filters and through the pump and blown out into the housing of the device or into the environment.

Accordingly, the above-mentioned method for detecting liquid entry in the case of positive liquid detection is followed by one or more of the following steps:

- replacement of the filter,

Replacement or checking of the portion of the vacuum connection between the filter and the inlet of the pump, if any,

- replacement or inspection of the pump, including the outlet,

- checking and possibly decontaminating the interior of the housing,

- Review and, where appropriate, decontamination of the environment in which the

Device was used.

It would also be conceivable to carry out the programming of the control unit in such a way that a reaction dependent on the intensity of the sensor signals takes place. This can be done, for example, such that sensor signals, which indicate a very small amount of liquid infiltrated, only in the memory of the

Control unit are stored so that they can be accessed during maintenance. On the other hand, sensor signals that indicate the ingress of a larger amount of liquid could lead to an immediate shutdown of the pump and, if necessary, to a blockage of the device for the user. The stored messages could be made available via remote data communication, for example in connection with remote maintenance of the device by a service center of the device manufacturer.

According to the above-described measures after the detection of

Liquid in downstream of the filter disposed portions of the fluid system, the present invention comprises the use of a liquid sensor, in particular an optoelectronic liquid sensor, in a device of the type described herein for detecting liquid entry in downstream of the filter disposed portions of the fluid system. The invention preferably comprises the use of a liquid sensor, in particular of an optoelectronic liquid sensor, for safety shutdown of the pump and / or for alerting a user and / or for storing the event in an electronic memory belonging to the electronic control unit. Under one

Safety shutdown of the pump is in this case an immediate deactivation of the pump in the detection of liquid in the downstream of the filter

arranged portions of the fluid system understood.

According to the invention, the liquid sensor with the control unit

can communicate because the detection of a fluid entry into the

arranged downstream of the filter portions of the fluid system by means of the control unit based on the sensor signal. The communication is preferably carried out by a direct electrical connection. The communication can also be realized by a different type of connection, for example by an optical connection (fiber optic) or wirelessly by radio link.

In the context of the invention disclosed herein, the device preferably comprises a fluid receptacle for receiving aspirated from the wound

Body fluids. Advantageously, the liquid receiving container is arranged in the vacuum connection between the filter and the connection for the suction line leading to the wound site. The container then has at least one inlet for feeding the body fluids and at least one outlet for

Exposure to negative pressure. The liquid receiving container serves to receive and store the liquids sucked from the wound site on the patient, for example wound exudate and / or rinsing liquid. The fluid receptacle is usually a disposable article which is discarded after the vacuum therapy. Advantageously, the manufacturer provides liquid receiving containers with different capacities. Smaller containers, for example with a capacity of 100 ml to 400 ml, could be provided for the mobile operation of the device, while larger containers, for example with a capacity of 400 ml to 2000 ml, then be used for a stationary operation.

In the area of the inlet for feeding the body fluids of the

Connection for the suction line leading to the wound site be attached. Alternatively, it is possible that at the inlet a conduit means is present, at its pointing to the patient's body end then the connection for the suction line is attached. In this case, the aforesaid conduit forms part of the vacuum connection between the port and the inlet of the pump. The vacuum connection is then placed over the interior of the container and the

Tank outlet over the filter up to the inlet of the pump.

The filter can be located directly in the area of the container outlet, which to

Exposure to negative pressure, be present. In particular, the filter may be firmly and permanently attached to the container. It would also be possible to connect the filter with the container outlet via a conduit means.

The device according to the invention can be used particularly advantageously in particular if the aspirated liquids are stored in the receptacle in liquid form until disposal. With the expression

"Storage in liquid form" means that in the container no

Thickening agents (also referred to as "trapping agents") are present.

In particular, the aspirated liquids are not stored in thickened form until disposal. Preferably, the liquid receiving container has in its interior by ribs or projections formed areas or mutually communicating chambers, so that the body fluids collected in the interior of the container are prevented in a movement of the container in the uncontrolled slosh. It has proved to be particularly advantageous when the device is a first

Housing part with a negative pressure generating means (pump) and a second housing part, which forms the liquid receiving container and which is manually attachable to the first housing part of the device and manually detachable from the first housing part of the device comprises. Advantageously, the manufacturer, the second housing parts (liquid receptacle) with

different capacities. Smaller containers, for example with a capacity of 100 ml to 400 ml, could be provided for the mobile operation of the device, while larger containers, for example with a capacity of 400 ml to 2000 ml, then be used for a stationary operation. The same first housing part can then be combined as needed with different second housing parts, so that the

Therapy device, which forms the first housing part, both for mobile operation and for stationary operation, for example in the hospital, can be used.

In the first housing part should in addition to the pump, inter alia, the

Control unit, the liquid sensor and possibly a power supply to be accommodated. For the power supply used to operate electrical or electronic components (eg pump, fluid sensor,

Control unit or controls) is required, it may in particular be a power supply and / or a battery. Furthermore, at the first

Housing part controls for the device (means for operating the control unit by a user), in particular a touch screen display, be present.

According to the invention it is preferred if all components of the therapy device are housed or provided on the or in the first housing part, which are provided for a permanent use. In contrast, the second housing part preferably comprises the intended for single use components of the therapy device, namely the liquid receptacle and either the connection for the suction line, which is located directly on the container or a line leading to the connection including the connection.

Furthermore, the second housing part preferably comprises the filter so that it can be disposed of together with the container. According to a special

preferred embodiment, the filter is arranged directly at the outlet of the liquid receiving container.

The electronic fluid sensor is a sensor suitable for detecting fluid. In particular, the sensor must be suitable for detecting liquid present in a closed interior. suitable

Sensor types for the detection of liquid include, for example, sensors which are based on the measurement of light (optoelectronic sensors), sensors which are based on the measurement of the electrical capacitance (capacitive sensors) or sensors which detect liquid due to a change in the electrical conductivity (conductive sensors ) can prove. Preferably, in connection with the present invention a

optoelectronic liquid sensor used as an optoelectronic

Liquid sensor has a suitable sensitivity and very fast (in

Millisecond range) is responsive to the presence of liquid or liquid droplets in the measurement path. The presence of liquid in the tube is detectable by a change in the optical density (transmission) or by a change in the refraction of the light.

Photocells that register a change in transmission are commercially available and very cost effective. The fluids to be detected are, in particular, body fluids, rinsing fluids or mixtures thereof. Body fluids are usually colored and can easily be detected by a light barrier. The rinsing liquids used, for example, for instillation therapy, on the other hand, are clear liquids (saline solutions) which less dampen the transmission. For the detection of clear liquid in the interior of a conduit means, the measurement should therefore take place at a wavelength which is sufficiently absorbed by an aqueous solution, For example, in the UV range at less than 240 nm or in the long-wavelength range at more than 600 nm. Even more sensitive measurements are possible by means of a change in the refraction, usually a laser photoelectric sensor is used. Sensor modules with laser light barriers are likewise commercially available. When using an optoelectronic liquid sensor, it has proved to be particularly advantageous if that portion of the vacuum connection, which is located between the filter and the inlet, is formed by a transparent tube and the sensor is attached to the outside of the transparent tube. When using optical sensor means should the

Liquid sensor may be housed in a darkened area of the device, since the detection of liquid in the hose could otherwise be disturbed by ambient light. The darkening can be done by a housing in which the

Liquid sensor and the other electronic components of the device are housed. Commercially available liquid sensors comprising a light source and a phototransistor are suitable for practical use. As the light source, an LED lamp is usually used. The light source and the phototransistor are with a hose holder to a sensor assembly

summarized and arranged such that when inserted tube suitable for the measurement positioning of the optical elements is ensured. The assembly may include a calibration module for manufacturing-related

Differences in the optical elements to compensate for changes in the optical elements due to aging and fluctuations in the power supply.

Furthermore, the sensor assembly may be mounted on a circuit board, for example on the board, which also carries the control unit. One for the present

Invention suitable electronic liquid sensor with LED, phototransistor and hose holder is available, for example, under the name OPB350 from OPTEK Technology Inc. (USA). Based on the electrical signals output by the liquid sensor ("sensor output"), it is possible to differentiate the states "no liquid present" and "liquid present." Threshold values of the sensor output serve to delimit the different states, their exceeding or undershooting by the control unit Presence or absence of liquid in the relevant section of the fluid system are interpreted.

Alternatively or additionally, it is possible to use the time change of the sensor output, which is present on the optoelectronic sensor, for the detection of liquid in the vacuum connection. The present invention therefore includes a method of detecting liquid intrusion downstream of the filter disposed portions of the fluid system, wherein the present on the optoelectronic sensor temporal change of the sensor output by the electronic control unit is then evaluated as liquid penetration, if a rapid increase or a rapid drop in sensor output (measured as voltage or current) occurs. Here, under a rapid increase or decrease, a change in the voltage applied to the sensor or the current flowing through the sensor by more than 10% per minute, preferably more than 10% per 1 second, more preferably more than 10% per 0 , 1 second, in particular by more than 10% per 10 milliseconds, understood. The evaluation of the time available on the optoelectronic sensor change of the sensor output allows a very fast and sensitive detection of liquid entry into the respective sections of the fluid system. A quick detection of the

Liquid entry is advantageous because the control unit then provided

Measures, such as emergency shutdown of the pump, to an early

Time can initiate.

In connection with the detection of the liquid ingress on the basis of the temporal change of the sensor signals d (sensor output) / dt (for example the temporal change dU / dt of the voltage measured in V / s at the optoelectronic sensor), a suitable threshold value for the state "fluid present" are determined. The threshold, which is indicated for example in the unit volts per second (V / s), then serves to detect the liquid entry, so that, for example, issued an alarm message and the pump is deactivated. To determine a suitable

Threshold is first determined the fluctuation of the sensor output. This is preferably done when the measuring area (for example a tube section) is dry is. The standard deviation σ of the sensor signals is determined from the measured values. The threshold value for the rate of change (d (sensor output) / dt) is then obtained by multiplying the determined standard deviation σ by a suitable multiplication factor. It has been shown that the multiplication factor should be between 5 and 20 in order to ensure sensitive and error-free detection. Preferably, the factor is 10 to 15, in particular 12 to 13. The detection method described here allows the very fast (in the millisecond range) detection of very small amounts of liquid (in the μΙ range), even if the liquid is in the form of very fine droplets.

According to a particularly advantageous embodiment of the invention, the device comprises an optoelectronic liquid sensor, which can detect a change in the transmission and / or refraction due to a liquid. The sensor is arranged in that section of the vacuum connection which is located between the filter and the inlet of the pump, the section being formed by a transparent hose, in particular by a silicone hose.

In this case, the sensor is mounted on the outside of the transparent tube, so that the presence of liquid in the tube causes a detectable by the sensor change in the transmission and / or refraction. The electronic control unit then evaluates the sensor signals (sensor output) as ingress of liquid into the relevant section of the vacuum connection when a preset threshold for the time change of the

Sensor signals (d (sensor output) / dt) is exceeded. The threshold value in this case is 3 times to 30 times, in particular 5 times to 20 times, particularly preferably 10 times to 15 times, very particularly preferably 12 times to 13 times the standard deviation σ, where the standard deviation σ is determined on the basis of at least 5 consecutive measurements of the sensor output of a sensor applied to a dry hose. At the here mentioned

Sensor signals (sensor output) are preferably those on the

optoelectronic sensor measured voltage U in volts. As a temporal change The sensor signals are then the time change of the voltage dU / ds in volts per second (V / s).

A suitable detection method may optionally also be simultaneous

Evaluation of both threshold values and temporal change rates of the sensor output include: Accordingly, the control unit interprets the

Sensor output then as liquid entering the vacuum connection when either absolute thresholds of the sensor output are exceeded or fallen below or when the rate of change exceeds a preset value.

The present invention further relates to a method for negative pressure therapy of

Wounds comprising the steps:

i) providing a device according to the invention,

ii) performing the negative pressure therapy,

ii) monitoring the downstream of the filter arranged sections of the

Fluid system by means of a liquid sensor,

iv) In the case of detection of liquid entry into the downstream of the filter disposed portions of the fluid system one or more maintenance and / or security measures such as:

- Output of a warning signal on the device (visually and / or acoustically)

- Safety shutdown of the pump

- Lock the vacuum unit for the user, with a reset of the lock is only possible by a service technician (for example, by entering a code)

Replacement of the filter or the section leading to the pump

Vacuum connection

- Check, replace or dispose of the pump including the outlet

- Check and if necessary decontamination of the housing interior - Disposal of the vacuum therapy unit

Device was used.

The apparatus described herein may additionally include a liquid indicator for indicating and / or detecting liquid which has entered portions of the fluid system disposed downstream of the filter. In this context, a liquid indicator is understood as meaning a substance which exhibits a color change or a color change after the liquid has been absorbed. The color change can also be a change in color intensity. The indicator substance is normally applied to a carrier. It would also be possible to apply the substance directly to components of the vacuum connection, for example to the inside of a conduit means. One

Liquid indicator, in which the penetration of liquid is already visible to the naked eye, can be provided as an additional security measure. It is also conceivable to detect the color change or the color change likewise electronically. This can be done by means of the liquid sensor already present in the device according to the invention or by means of an additional optoelectronic sensor. Furthermore, it may prove advantageous to have an additional

Fluid indicator, which is provided inside the housing of the device, but outside the fluid system to provide. Such an indicator can give the maintenance personnel an indication that the device undesirable with

Liquid has come into contact. Such liquid indicators are known from the prior art and are used regularly, for example, in mobile phones.

Further details, features and advantages of the invention will become apparent from the appended claims, the drawings and the following description of exemplary embodiments of the invention. characters

Figure 1 shows a simply configured embodiment of the device according to the invention.

Figure 2 shows another embodiment of the present invention.

FIG. 3 shows an embodiment of the device according to the invention comprising a first housing part and a second housing part.

Figure 4 shows a suitable for use in the device according to the invention

Sensor module with optoelectronic sensor and hose holder.

FIG. 5 a shows the sensor output (in V) determined during a test as a function of the presence or absence of water in a plastic tube. FIG. 5 b shows the time change rate of the sensor output (in V / s) determined during an experiment.

FIG. 6 shows a warning message which can be output after the detection of liquid.

reference numeral

1 pump

2 Inlet of the pump for drawing in air

3 outlet of the pump for blowing out air

4 Connection for a suction line leading to the wound site

5 vacuum connection

6 filters

7 Electronic control unit

8 Electronic fluid sensor

9 fluid receptacle

10 Device for providing negative pressure

1 1 Connection between pump and control unit

12 Connection between liquid sensor and control unit

14 silencers 15 wound site

16 Air-impermeable wound cover

17 negative pressure fitting (port)

18 suction line

20 Apparatus for supplying negative pressure connected to a vacuum dressing

22 power supply

23 touchscreen display

24 connecting means

25 Body fluids extracted from the wound

26 inlet for feeding the body fluids

27 Output for admission with negative pressure

30 A comprising a first housing part and a second housing part

contraption

31 First housing part

32 second housing part

40 sensor module

FIG. 1 shows a schematic representation of a device 10 according to the invention for providing negative pressure. The device comprises an electronic

Control unit 7 and an electrically driven or electrically driven pump 1 with an inlet 2 for sucking in air and an outlet 3 for blowing out air. Furthermore, the device comprises a connection 4, a filter 6, a liquid sensor 8 and a vacuum connection 5

Liquid sensor 8 communicates via the connection 12 with the control unit 7. The control of the pump 1 by the control unit 7 via the connection 1 1. In the connection 1 1 and / or the connection 12 may be a

electrical connection or to act a wireless connection.

A negative pressure communication between the wound site (not shown in FIG. 1) and pump 1 can be established via port 4. The connection 4 is For example, a conventional quick disconnect connector for plastic tubing. To establish a vacuum communication, a suction line 18 is connected via the connection 4 with the vacuum connection 5. The vacuum connection 5, which allows a negative pressure communication between the inlet 2 of the pump and the port 4, consists in the embodiment shown in Figure 1 of three sections, namely the portion between terminal 4 and the filter 6, the portion between the filter 6 and liquid sensor eighth and the section between liquid sensor 8 and pump 1. The vacuum connection of a

The device according to the invention may comprise further sections, as shown for example in FIG. The individual sections of the vacuum connection can

Conductive means, such as plastic tubing include. It is also possible to combine one or more of the named components in a single component. For example, the terminal 4 and the filter 6 could be realized in a single component, so that no conduit means must be present between these elements.

Figure 2 shows a further embodiment of the device according to the invention in a schematic representation, wherein the device designated by reference numeral 20 is connected via the terminal 4 to a vacuum dressing. Of the

Vacuum bandage includes an air-impermeable wound cover 16, a

Vacuum fitting (port) 17 and suction line 18. The vacuum dressing was applied to a wound site 15, the wound site 15 comprising the wound to be treated and the patient's intact skin surrounding the wound. In addition to the embodiment shown in FIG. 1, that shown in FIG

Device a liquid receptacle 9, in which the extracted from the wound of the patient body fluids 25, preferably in liquid form, are collected. In the interior of the liquid receiving container 9, regions formed by ribs or projections or communicating chambers may be present, so that the collected body fluids are prevented from uncontrolled sloshing during a movement of the container. The liquid receiving container has an inlet 26 for feeding the

Body fluids and an outlet 27 for pressurizing the container with negative pressure. Correspondingly, in the embodiment shown in FIG. 2, the vacuum connection 5 comprises a further section, namely the interior of the liquid receiving container 9. The outlet 27 is arranged in the upper region of the liquid receiving container 9.

Between the container 9 and the pump 1, as is conventional in the art, there is a filter 6 which, when intact, can prevent the ingress of liquid into the section of the vacuum connection 5 leading to the pump and further downstream. In order to be able to detect liquid sucked in the direction of the pump 1 in the case of a filter 6 which does not function properly, a liquid sensor 8 is provided between the filter 6 and the inlet 2 of the pump 1. One

Liquid passage through the filter can occur, for example, in a filter which has already been delivered defective manufacturer. Furthermore, it is possible for a filter to break through during operation. Finally, it would be conceivable that due to a faulty operation of the device by the user no filter was used at all. The electronic control unit 7, which with the

electronic liquid sensor 8 communicates via the connection 12 (electrically or wirelessly) evaluates the sensor output from the liquid sensor 8 to the

To be able to detect penetration of liquid. Furthermore, the electronic control unit 7 via the connection 1 1, the pump 1 (electrically or wirelessly) control. By the term "steer" here is meant that the electronic

Control unit 7 can start or stop the pump and regulates the speed of the pump. To control the negative pressure operation by the electronic control unit 7, operating parameters of the pump could optionally also be used, for example a tachometer signal output by the pump or the current consumption of the pump. Accordingly, it is also possible to exchange signals in the bidirectional direction via the connection 11. It is also conceivable to supply the electric pump 1 via the connection 1 1 at the same time with electricity, in which case an electrical connection is required. In the case of a detection of liquid by the liquid sensor 8, the electronic control unit 7 can deactivate the pump 1 in order to prevent liquid from being sucked in and, if appropriate, an expulsion of body fluids via the outlet 3 into the interior of the appliance (and possibly additionally into the environment of the appliance) , Alternatively or additionally, the control unit 7 output a warning signal (optically or acoustically) to alert the user to the defective filter 6. Furthermore, the detected event can be recorded in a memory belonging to the electronic control unit 7 (not shown in FIG. 2). The electronic control units 7 may be connected to control elements, in particular to a touchscreen display 23. The user of the device can control the therapy device via the controls and program if necessary. In addition, the electronic control unit may include interfaces (eg, a USB port) such that external electronic components, such as a portable computer, may communicate with the computer

Control unit 7 can communicate. The interfaces are not shown in FIG. The component 22 is a power supply, which normally comprises a rechargeable accumulator for the mobile operation of the device and a power supply. By means of the power supply 22, the electrically driven or electrically driven pump 1, the electronic control unit 7 and other electronic or electrical components such as the touch screen display 23 can be supplied with power.

FIG. 2 shows an optional silencer 14 which is connected to the outlet 3 of the pump 1 in order to reduce the operating noise of the device. The muffler 14 may be odor absorbing substances,

For example, activated carbon, to avoid odor during operation of the device. In the example shown in Figure 2, the fluid system of the device extends from port 4 to the downstream port of muffler 14, which communicates with the atmosphere. The fluid system of the device 20 may in turn be connected to the fluid system of the patient side

Components (16, 17, 18) communicate when the vacuum bandage is sealingly connected via terminal 4 to the therapy device. Corresponding is then a continuous fluid system is produced between the wound space of the patient and the opening of the muffler 14, wherein in the section between wound space and pump 1 during operation of the pump 1, a relative to the surrounding atmosphere reduced air pressure (negative pressure) is present. Fluids (especially wound secretions and air) are then used in the intended use of the

Device in the negative pressure therapy, starting from the wound downstream in the direction of the liquid receiving container 9 sucked.

Figure 3 shows a schematic representation of a further preferred embodiment of the device with a first housing part 31 and a second housing part 32. The first housing part 31 comprises in addition to the negative pressure generating electrically driven or electrically driven pump 1 usually provided for repeated use components, ie in particular the liquid sensor 8, the electronic control unit 7, the power supply 22 and the touch screen display 23. Thus, the single-use components of the device, namely liquid receptacle 9 with filter 6 and port 4 (and any existing

Conduit between container 9 and port 4), to the multiple

Use provided further components coupled or separated from these.

Normally, the first housing part 31 comprises a housing in which or on which the aforementioned components are housed. The second housing part 32 forms the liquid receiving container 9 and may comprise further components, for example the connection 4 or alternatively a line leading to the connection 4 (including the connection 4). The second housing part 32 is manually attachable to the first housing part 31 of the device and of the first housing part 31 of the

Device manually detachable. The detachable connection of the two housing parts (31, 32) is preferably accomplished by means of a coupling means 24. This may be, for example, a snap-in and manually releasable by actuators locking. As shown in Figure 3, the filter 6

preferably directly at the outlet 27 of the liquid receiving container 9 appropriate. In this case, the filter 6 should have on its side facing the pump 1 a coupling element suitable for producing a pressure-tight connection, for example an annular seal, so that a vacuum communication between the container and the pump-side section of the vacuum connection 5 can be produced simultaneously when the housing parts are joined together ,

FIG. 4 illustrates a sensor module 40 with an optoelectronic sensor and hose holder which is suitable for use with the device according to the invention. The optoelectronic sensor (not shown in FIG. 4) is integrated in the sensor module 40. The sensor module 40 can either be applied directly to the main board of the device, which also carries the electronic control unit 7, or alternatively be connected to the electronic control unit by means of an electrical connection. In the sensor module 40 can be arranged between the filter 6 and inlet 2 of the pump 1 conduit portion which a portion of

Vacuum connection 5 forms to be trapped. Sensor modules suitable for the device are commercially available (for example OPB350 sensor from OPTEK Technology Inc., USA). FIG. 5 a shows, by way of example, the sensor output in volts determined in a test as a function of the presence or absence of water in one

Plastic hose. A higher output corresponds here to a higher light intensity measured at the sensor. For the experiment, a plastic tube made of silicone with an outside diameter of 10 mm and an internal diameter of 6 mm was clamped in the holder of an OPB350 OPTEK sensor. Shown is the

Sensor output measured in volts for a dry hose (sections ii and iv of the diagram) and for passing water through the hose (section iii) of the diagram). Section i shows the sensor output before the hose has been clamped. The diagram shows a very fast response of the sensor signal to the presence or absence of water in the hose. The rise or fall of the signal takes place in less than 200 milliseconds. The ratio of Sensor output when comparing states ii (dry) and iii (water) is about 2.5. The absolute sensor output is significantly influenced by the transparency (transmission) of the liquid present in the hose and by the material of the hose. In the experiment shown here, the sensor output first drops after insertion of the tube into the holder (sections i and ii) as the tube absorbs and scatters light. After passing through water, the sensor output increases because the water focuses the light beam. If a cloudy liquid, such as blood, is present in the tube, the sensor output will drop as compared to a dry tube (not shown in Figure 5). In the evaluation of the

Sensor outputs, therefore, the transmission of the liquid to be detected is observed. In particular, the transmission of the liquid to be detected must be taken into account when setting threshold values for the states "no liquid in the tube" or "liquid inlet". However, in a negative pressure therapy with different indications or even in the course of a single therapy a variety of fluids can be sucked out of the wound area, for example blood, purulent secretions or aqueous rinsing fluids (in instillation therapy). This can lead to difficulties in setting the above (absolute) thresholds. It is therefore more advantageous that

Interpretation of the sensor data on the basis of the temporal change of the sensor output (d (sensor output) / dt) perform, where appropriate, in addition to absolute

Thresholds could be used. FIG. 5 b shows, by way of example, the detection of liquid on the basis of the rate of change in time of the voltage dU / dt measured at the sensor. Incidentally, the experimental setup corresponds to the situation shown in FIG. 5 a. The measurement of the sensor output took place at intervals of 10 milliseconds.

Decisive for an error-free detection of liquid entry into the hose and to avoid false positive messages is the determination of a suitable

Threshold for the rate dU / dt, for example in volts per second (V / s). For this purpose, the standard deviation σ of the values determined for the rate of change dU / dt was first calculated. The measurement was carried out using a dry tube. The threshold (dU / dt) is then multiplied by the Standard deviation σ obtained with a suitable multiplication factor. The multiplication factor should be between 5 and 20 if possible. Preferably, the factor is 10 to 15, in particular 12 to 13.

In the present example (FIG. 5 b), a standard deviation σ of 40.626 was determined when measuring the sensor fluctuation (dry tube). For this purpose, 1000 consecutive measured values were used (measurements were taken at a distance of 10 milliseconds). The threshold (dU / dt) = 500 V / s was therefore set as the threshold value for the detection of liquid entry into the hose. This value corresponds to 12.3 times the standard deviation σ.

In the time window of the measurement shown in FIG. 5 b, the threshold value was exceeded after 70 milliseconds:

Time (s) rate of change dU / dt in V / s

0 -6.00

0.01 12.00

0.02 46.00

0.03 68.00

0.04 66.00

0.05 48.00

0.06 -6.00

0.07 -7518.00

0.08 -13166.00

0.09 -16920,00

0, 1 -18828,00

0, 1 1 -18840,00

0, 12 -16964,00

0, 13 -13168,00

0, 14 -7502,00

0, 15 -8.00

0, 16 24.00

0, 17 48.00

0, 18 72.00 0, 19 56.00

0,2 40,00

0.21 14.00

0,22 10,00

0,23 -26,00

The maximum rate of change dU / dt is -18840.00 V / s.

FIG. 6 shows, by way of example, a warning message displayed on the touchscreen of the vacuum therapy unit, which according to a particularly preferred embodiment

Embodiment of the invention can be issued to a response of the liquid sensor out. According to this embodiment, a sensor signal of the liquid sensor leads to the immediate shutdown of the pump to output the

Warning message and to block the negative pressure therapy unit for the user. In the example of a warning message shown here, the event detected by the sensor is displayed to the user as a (technical) problem ("problem-detected"). Unlocking the vacuum therapy unit and canceling the warning message can only be accomplished by a service technician of the equipment manufacturer, not by the user himself. This is a

Safety measure, which should ensure that a possibly with

Wound-secreted contaminated device is no longer used and instead checked expertly. The appearance of the warning message on the touch screen should be combined with an audible warning to alert the user to the problem.

Claims

claims

1. On the body of a user portable and / or stationary device (10, 20, 30) for providing negative pressure for the negative pressure therapy of wounds on

human or animal body, comprising i) a negative pressure generating electrically driven pump (1) having an inlet (2) for sucking in air, an outlet (3) for blowing out air and an interior which communicates with the inlet (2 ii) a connection (4) for a suction line leading to the wound site (18), iii) a vacuum connection (5) between the connection (4) and the inlet (2), so that a Negative pressure communication between the pump (1) and the leading to the wound site suction line (18) can be produced, iv) at least one filter (6), which in the intact state for liquids

v) an electronic control unit (7) for the pump (1), characterized in that the device (10, 20, 30) further comprises at least one electronic control unit (7) for the pump (1) Liquid sensor (8) connected to the control unit (7)

can communicate, wherein the at least one liquid sensor (8) is arranged downstream of the filter (6).

2. Device (10, 20, 30) according to claim 1, wherein the at least one

Liquid sensor (8) between the filter (6) and the inlet (2) of the pump, in the interior of the pump and / or in the region of the outlet (1) is arranged.

A device (10, 20, 30) according to claim 1 or 2, further comprising a fluid receiving container (9) for receiving aspirated from the wound Body fluids, wherein the liquid receiving container (9) in the

Vacuum connection (5) between the filter (6) and the connection (4) for the leading to the wound site suction line (18) is arranged and wherein the

Liquid receiving container (9) has at least one inlet (26) for feeding the body fluids and at least one outlet (27) for applying negative pressure.

4. Device (10, 20, 30) according to claim 3, wherein the

Liquid receiving container (9) in its interior by ribs or projections formed areas or communicating with each other chambers, so that in the interior of the liquid receiving container (9) collected body fluids are prevented in a movement of the liquid receiving container (9) from uncontrolled sloshing.

5. Device (10, 20, 30) according to any one of the preceding claims 3 or 4, wherein the device comprises a first housing part (31) with the negative pressure generating pump (1) and a second housing part (32), wherein the second housing part the liquid receiving container (9) and wherein the second housing part (32) on the first housing part (31) of the device (30) manually attachable and from the first housing part (31) of the device (30) is manually releasable.

6. Device (10, 20, 30) according to claim 5, wherein in the first housing part (31) next to the pump, the electronic control unit for the pump (1), a

Power supply (22) and means for operating the control unit (7) are housed by a user.

7. Device (10, 20, 30) according to one or more of the preceding

Claims 3 to 6, wherein the filter (6) directly at the output (27) of the

Liquid receiving container (9) is arranged.

8. Device (10, 20, 30) according to one or more of the preceding

Claims, wherein the electronic liquid sensor (8) is an opto-electronic sensor, a capacitive sensor or a conductive sensor.

Device (10, 20, 30) according to claim 8, wherein the electronic liquid sensor (8) is an optoelectronic liquid sensor capable of detecting a transmission or refraction altered by a liquid.

10. Device (10, 20, 30) according to claim 9, wherein the portion of the

Vacuum connection (5), which is located between the filter (6) and the inlet (2) is formed by a transparent tube and wherein the sensor (8) is attached to the outside of the transparent tube, so that the

Presence of fluid in the tube is detectable by a change in transmission or refraction.

1 1. A device (10, 20, 30) according to claim 10, wherein a through the

Optoelectronic sensor (8) measured change in transmission or refraction by the electronic control unit (7) then as liquid penetration into the downstream of the filter (6) arranged portion of the

Vacuum connection (5) is evaluated when a rapid increase or a rapid drop in the sensor output (measured as voltage or current) occurs, with a rapid increase or decrease, a change in the sensor (8) applied voltage or the current flowing through the sensor (8) is understood to be more than 10% per minute.

12. Device (10, 20, 30) according to one or more of the preceding

Claims, wherein the electronic control unit (7) can deactivate the pump (1) immediately after a detection of liquid which has penetrated downstream of the filter (6).

13. Device (10, 20, 30) according to one or more of the preceding

Claims, wherein the device (10, 20, 30) additionally comprises a liquid indicator for indicating and / or detecting liquid which has penetrated downstream of the filter (6).

14. Use of an optoelectronic sensor (8) in a device (10, 20, 30) according to one or more of the preceding claims 9 to 13 for the detection of liquid inlet downstream of the filter (6) and / or

Safety shutdown of the pump (1) and / or to lock the device and / or to alert a user.

15. Use of an optoelectronic sensor (8) in a device (10, 20, 30) according to one or more of the preceding claims 9 to 13 for the detection of liquid inlet downstream of the filter (6) in the context of a

Security check or maintenance of the device (10, 20, 30).